p.1
Sliding Filament Model of Muscle Contraction
What happens during muscle contraction according to the sliding filament model?
A myosin head attaches to a binding site on the actin filament, forming a cross-bridge.
p.25
Types of Muscle Contractions
What is a myogram?
A graphical representation of muscle contractions.
p.2
Sliding Filament Model of Muscle Contraction
What is the state of a muscle when it is relaxed?
The muscle is in a relaxed state, with minimal tension.
p.30
Muscle Fiber Types: Fast vs. Slow
What are the characteristics of smooth muscle cells?
Elongated with tapered ends, lack striations, and have a relatively undeveloped sarcoplasmic reticulum.
p.28
Types of Muscle Contractions
What allows for the performance of daily activities?
Sustained contraction of muscles.
p.23
Types of Muscle Contractions
What is a myogram?
A graphical representation of muscle contraction over time.
p.20
Muscle Fiber Types: Fast vs. Slow
What is hypertrophy in skeletal muscles?
Enlargement of a muscle due to repeated exercise.
p.20
Types of Muscle Contractions
How does low intensity exercise affect slow muscle fibers?
It increases mitochondria and capillaries, making them more fatigue-resistant while maintaining size and strength.
p.16
Oxygen Supply and Cellular Respiration
What is another term for oxygen debt?
Excess post-exercise oxygen consumption.
p.20
Muscle Fiber Types: Fast vs. Slow
Does the number of skeletal muscle fibers change with hypertrophy or atrophy?
No, the number of skeletal muscle fibers does not change.
p.16
Oxygen Supply and Cellular Respiration
How does physical training affect muscle energy production?
It helps to increase a muscle’s capacity to improve energy production.
p.32
Role of Myosin and Actin in Muscle Contraction
What is the structure of cardiac muscle cells?
Branching, striated cells that interconnect in three-dimensional networks.
p.25
Types of Muscle Contractions
What are twitches in muscle contraction?
A single, brief contraction of a muscle fiber.
p.25
Types of Muscle Contractions
What is tetany?
A sustained muscle contraction resulting from rapid stimulation.
p.29
Types of Muscle Contractions
What is an isotonic contraction?
A contraction that involves shortening of the muscle while maintaining the same tension.
p.18
Heat Production and Muscle Fatigue
What happens to the heat produced during cellular respiration?
It is carried by the blood to other tissues to help maintain body temperature.
p.29
Types of Muscle Contractions
What characterizes isometric contraction?
Force generation without shortening of the muscle.
p.12
Energy Sources for Muscle Contraction
How does creatine phosphate help in energy production?
It transfers its phosphate group to ADP to regenerate ATP.
p.29
Types of Muscle Contractions
What is an example of isometric contraction?
Holding a weight in one position.
p.30
Muscle Fiber Types: Fast vs. Slow
How are thick and thin filaments arranged in smooth muscle cells?
They are arranged more randomly compared to other muscle types.
p.30
Muscle Fiber Types: Fast vs. Slow
What is multiunit smooth muscle?
Smooth muscle where fibers occur separately, found in blood vessels and the iris of the eye, stimulated by neurons and some hormones.
p.23
Types of Muscle Contractions
What is the significance of studying a myogram?
It helps in understanding the timing and strength of muscle contractions.
p.31
Neuromuscular Junction and Action Potential
What stimulates both smooth and skeletal muscle contractions?
Membrane impulses and an increase in calcium ions.
p.4
Calcium Ion Release and Muscle Contraction
What structure releases calcium ions during muscle contraction?
Sarcoplasmic reticulum (SR).
p.13
Oxygen Supply and Cellular Respiration
What is glycolysis?
The first phase of cellular respiration that is anaerobic and occurs in the cytoplasm.
p.4
Calcium Ion Release and Muscle Contraction
What is the role of calcium ions in muscle contraction?
They bind to troponin, exposing active sites on actin filaments.
What is summation in muscle fibers?
A process where a muscle fiber receives a series of stimuli of increasing frequency, leading to a greater force of contraction than a single twitch.
p.33
Muscle Fiber Types: Fast vs. Slow
What are the three types of muscle tissue?
Skeletal, Smooth, Cardiac.
p.1
Energy Sources for Muscle Contraction
What provides energy for the cross-bridges during muscle contraction?
The conversion of ATP to ADP by the enzyme ATPase.
p.7
Neuromuscular Junction and Action Potential
What happens to acetylcholine in response to an impulse in the motor neuron?
It is released into the synaptic cleft.
p.33
Types of Muscle Contractions
What is the major function of smooth muscle?
Movement of viscera, peristalsis, vasoconstriction.
p.19
Muscle Fiber Types: Fast vs. Slow
How do slow muscle fibers differ in terms of fatigue resistance?
They are resistant to fatigue and provide prolonged contraction.
p.9
Neuromuscular Junction and Action Potential
How does the impulse travel within the muscle fiber after stimulation?
It travels over the surface and deep into the fiber through the transverse tubules.
p.11
Energy Sources for Muscle Contraction
What happens to creatine phosphate as ATP decomposes?
Its energy is transferred to ADP, converting it back to ATP.
p.27
Neuromuscular Junction and Action Potential
What are motor units composed of?
Motor neurons and the muscle fibers they innervate.
p.35
Role of Myosin and Actin in Muscle Contraction
What feature do myosin molecules have that interacts with thin filaments?
Globular heads that extend toward nearby thin filaments.
p.27
Neuromuscular Junction and Action Potential
What is the function of motor units?
To control muscle contractions.
p.30
Muscle Fiber Types: Fast vs. Slow
What is visceral smooth muscle?
Smooth muscle that occurs in sheets, found in the walls of hollow organs, and can stimulate one another displaying rhythmicity.
p.27
Neuromuscular Junction and Action Potential
What happens when a motor neuron fires?
All muscle fibers in that motor unit contract.
p.10
Muscle Relaxation Mechanisms
What happens to calcium ions during muscle relaxation?
They are actively transported into the sarcoplasmic reticulum.
p.20
Types of Muscle Contractions
What happens to fast muscle fibers during forceful exercise?
They increase the number of actin and myosin filaments, enlarging fibers and the entire muscle for stronger contractions.
p.8
Muscle Relaxation Mechanisms
What role does ATP play in muscle relaxation?
ATP binds to myosin heads, breaking the linkages between myosin and actin.
p.18
Muscle Fatigue and Heat Production
What is muscle fatigue?
The loss of a muscle's ability to contract during strenuous exercise.
p.31
Neuromuscular Junction and Action Potential
Which neurotransmitters affect smooth muscle contraction?
Both acetylcholine (ACh) and norepinephrine.
p.18
Muscle Fatigue and Heat Production
What factors may contribute to muscle fatigue?
Electrolyte imbalances and decreased ATP levels.
p.31
Muscle Relaxation Mechanisms
How does smooth muscle contraction differ from skeletal muscle contraction in terms of hormonal influence?
Hormones can stimulate or inhibit smooth muscle contraction, but not skeletal muscle.
p.21
Neuromuscular Junction and Action Potential
What does one motor neuron impulse release at the neuromuscular junction?
Sufficient acetylcholine (ACh) to bring a muscle fiber to its threshold.
p.32
Role of Myosin and Actin in Muscle Contraction
How does the mechanism of contraction in cardiac muscle compare to skeletal and smooth muscle?
It is essentially the same, but with some differences.
p.12
Energy Sources for Muscle Contraction
Why is ATP important for muscles?
It provides energy for muscle contraction.
p.32
Calcium Ion Release and Muscle Contraction
What is a key difference in the sarcoplasmic reticulum of cardiac muscle?
It is not well-developed and does not store much calcium.
p.32
Calcium Ion Release and Muscle Contraction
What role do transverse tubules play in cardiac muscle?
They supply extra calcium from extracellular fluid, allowing longer twitches.
p.12
Energy Sources for Muscle Contraction
What is the role of the phosphate group released from creatine phosphate?
It is transferred to ADP to form ATP.
p.11
Energy Sources for Muscle Contraction
What is the primary energy source for muscle fiber contraction?
ATP (adenosine triphosphate).
How does summation affect muscle contraction?
It allows for a greater total contraction force by accumulating the force of each twitch.
p.17
Energy Sources for Muscle Contraction
What pathway is used during low to moderate intensity exercise?
Glycolysis leading to pyruvic acid formation and aerobic respiration.
p.19
Muscle Fiber Types: Fast vs. Slow
What is the primary function of slow muscle fibers?
To provide sustained, prolonged contractions.
p.6
Types of Muscle Contractions
What is the primary focus of the content?
Skeletal Muscle Contraction.
p.14
Energy Sources for Muscle Contraction
What are the two processes through which muscle cells produce ATP?
Glycolysis (anaerobic process) and the citric acid cycle (aerobic process).
p.3
Sliding Filament Model of Muscle Contraction
What is the primary function of a sarcomere in muscle contraction?
To shorten and generate force during muscle contraction.
p.25
Types of Muscle Contractions
What is summation in muscle contractions?
The process where successive stimuli increase the strength of muscle contractions.
p.8
Muscle Relaxation Mechanisms
What continues the contraction of a muscle?
The continuation of the nerve impulse.
p.28
Muscle Relaxation Mechanisms
Why is muscle tone important?
For the maintenance of posture.
p.16
Oxygen Supply and Cellular Respiration
What does oxygen debt refer to?
The amount of oxygen required by liver cells to convert lactate back into glucose and by muscle cells to resynthesize ATP and creatine phosphate.
p.8
Calcium Ion Release and Muscle Contraction
What happens to calcium after the nerve impulse stops?
Calcium is returned to the sarcoplasmic reticulum using ATP.
p.21
Neuromuscular Junction and Action Potential
What is one method of studying muscle function?
Removing a single muscle fiber and connecting it to a device that records its responses to electrical stimulation.
p.22
Types of Muscle Contractions
What does a myogram record?
An electrically-stimulated muscle contraction.
p.8
Muscle Relaxation Mechanisms
What occurs to actin after the muscle relaxes?
Actin returns to its original position.
p.8
Calcium Ion Release and Muscle Contraction
Why is the return of calcium to the sarcoplasmic reticulum important?
It is a key step in muscle relaxation.
p.22
Types of Muscle Contractions
What follows the latent period in muscle contraction?
A period of contraction and a period of relaxation.
p.26
Recruitment of Motor Units
What is motor unit recruitment?
An increase in the number of activated motor units within a muscle at higher intensities of stimulation.
p.29
Types of Muscle Contractions
What is the relationship between isotonic and isometric contractions in most movements?
Most movements are a combination of both types of contraction.
p.26
Recruitment of Motor Units
What effect does recruitment have on muscle contraction?
It causes an increase in the strength of a contraction.
p.22
Role of Myosin and Actin in Muscle Contraction
What happens if the stimulus does not reach the threshold in muscle fibers?
The muscle fiber will not respond at all.
p.26
Recruitment of Motor Units
When does a muscle achieve maximum tension?
When all of its motor units have been recruited.
p.32
Neuromuscular Junction and Action Potential
What unique characteristic does cardiac muscle have regarding its contraction?
It is self-exciting and rhythmic.
p.34
Role of Myosin and Actin in Muscle Contraction
What is the structure of myosin?
Myosin consists of two twisted strands with globular heads projected outward.
p.24
Types of Muscle Contractions
Can complete tetany occur in the body?
No, it can only be accomplished in a lab.
p.34
Role of Myosin and Actin in Muscle Contraction
What is the structure of actin?
Actin is a globular protein arranged in twisted filaments (a double helix).
p.17
Energy Sources for Muscle Contraction
What pathway is used during high intensity exercise?
Glycolysis leading to lactic acid formation.
p.28
Types of Muscle Contractions
What are summation and recruitment in muscle contractions?
They can produce a sustained contraction of increasing strength.
p.28
Muscle Relaxation Mechanisms
What is muscle tone?
A continuous state of sustained contraction of a few motor units at a time within a muscle, even when at rest.
p.27
Neuromuscular Junction and Action Potential
How do motor units contribute to muscle strength?
By recruiting more muscle fibers for stronger contractions.
p.20
Muscle Fiber Types: Fast vs. Slow
What is atrophy in skeletal muscles?
Decrease in muscle size and strength due to disuse.
p.30
Types of Muscle Contractions
What physiological process is accomplished by visceral smooth muscle?
Peristalsis in tubular organs.
p.4
Neuromuscular Junction and Action Potential
What happens to the transmembrane potential of the muscle fiber when Ach binds to its receptors?
It changes, leading to the production of an action potential.
p.5
Muscle Relaxation Mechanisms
What initiates the end of a muscle contraction?
The generation of action potential ceases as acetylcholine (ACh) is broken down by acetylcholinesterase (AChE).
p.10
Muscle Relaxation Mechanisms
What occurs to the myosin heads during the breakdown of ATP?
The myosin heads are 'cocked'.
p.5
Calcium Ion Release and Muscle Contraction
What happens to calcium ions during the end of a muscle contraction?
The sarcoplasmic reticulum (SR) reabsorbs calcium ions, causing their concentration in the sarcoplasm to decline.
p.10
Muscle Relaxation Mechanisms
What molecules block the interaction between myosin and actin filaments during relaxation?
Troponin and tropomyosin.
p.5
Calcium Ion Release and Muscle Contraction
What occurs when calcium ion concentrations approach normal resting levels?
The troponin-tropomyosin complex returns to its normal position, covering the active sites.
p.21
Neuromuscular Junction and Action Potential
What is the role of acetylcholine (ACh) in muscle contraction?
It helps bring a muscle fiber to its threshold to trigger contraction.
p.12
Energy Sources for Muscle Contraction
What happens during the breakdown of creatine phosphate?
It releases a high-energy phosphate group.
p.1
Role of Myosin and Actin in Muscle Contraction
What occurs when the myosin head bends?
It pulls on the actin filament, moving it toward the center of the sarcomere.
p.18
Heat Production and Muscle Fatigue
What is the relationship between heat production and cellular respiration?
Heat production is a byproduct of cellular respiration.
p.1
Sliding Filament Model of Muscle Contraction
What happens to the sarcomere when many sarcomeres shorten simultaneously?
The muscle fiber shortens.
p.12
Energy Sources for Muscle Contraction
What physiological activities can the generated ATP be used for?
Various activities, including muscle contraction.
p.19
Muscle Fiber Types: Fast vs. Slow
What is the diameter of slow muscle fibers compared to fast fibers?
Slow fibers have a smaller diameter.
p.11
Energy Sources for Muscle Contraction
What role does creatine phosphate play in muscle contraction?
It helps regenerate ATP from ADP and phosphate.
p.15
Oxygen Supply and Cellular Respiration
What is oxygen used for during strenuous exercise?
To produce ATP for muscle contraction.
p.33
Types of Muscle Contractions
How does smooth muscle contract compared to skeletal muscle?
Contracts and relaxes slowly; single unit type is self-exciting and rhythmic.
p.23
Types of Muscle Contractions
What does a single muscle twitch represent?
A brief contraction of a muscle fiber in response to a stimulus.
p.31
Role of Myosin and Actin in Muscle Contraction
What is a similarity between smooth muscle contraction and skeletal muscle contraction?
Both involve a reaction between actin and myosin.
p.10
Muscle Relaxation Mechanisms
What role does ATP play in muscle relaxation?
It breaks cross-bridge linkages between actin and myosin filaments.
p.12
Energy Sources for Muscle Contraction
What is creatine phosphate?
A high-energy compound stored in muscles.
p.21
Neuromuscular Junction and Action Potential
What happens to isolated muscle fibers when exposed to stimuli of various strengths?
They remain unresponsive until the threshold stimulus is reached.
p.26
Recruitment of Motor Units
What is a motor unit composed of?
A motor neuron and the muscle fibers it controls.
p.21
Neuromuscular Junction and Action Potential
What is a threshold stimulus?
The minimum strength of stimulus required to generate an impulse through the muscle fiber, release calcium ions, activate cross-bridges, and contract the muscle.
p.26
Recruitment of Motor Units
What happens when a motor unit is stimulated?
The muscle fibers of the motor unit contract all at once.
p.18
Muscle Fatigue and Heat Production
How does lactic acid accumulation affect muscle fatigue?
It may decrease pH, contributing to muscle fatigue.
p.5
Role of Myosin and Actin in Muscle Contraction
What prevents further cross-bridge interaction during muscle contraction?
The covering of active sites by the troponin-tropomyosin complex.
p.18
Muscle Fatigue and Heat Production
What is a muscle cramp?
A sustained, painful, involuntary contraction of a muscle.
p.5
Types of Muscle Contractions
What is the result of the absence of cross-bridge interactions?
Further sliding cannot take place, and the contraction ends.
p.18
Muscle Fatigue and Heat Production
What causes a muscle cramp?
Changes in the extracellular fluid around muscle fibers, leading to uncontrolled stimulation by motor neurons.
p.5
Muscle Relaxation Mechanisms
What happens to the muscle after contraction ends?
Muscle relaxation occurs, and the muscle returns passively to its resting length.
p.22
Role of Myosin and Actin in Muscle Contraction
What does the all-or-none response imply about muscle fiber contraction?
A muscle fiber either contracts completely or not at all.
p.24
Types of Muscle Contractions
What is partial tetany?
A condition where relaxation time becomes very short due to higher frequency of stimulation.
p.15
Oxygen Supply and Cellular Respiration
What happens during 1-2 minutes of strenuous exercise?
Oxygen deficiency may develop.
p.17
Energy Sources for Muscle Contraction
What type of exercise has sufficient oxygen supply for cellular requirements?
Low to moderate intensity exercise.
p.9
Neuromuscular Junction and Action Potential
What happens when ACh binds to its receptors in the muscle fiber membrane?
The sarcolemma is stimulated.
p.19
Muscle Fiber Types: Fast vs. Slow
What is the primary function of fast muscle fibers?
To perform rapid movements and reach maximum force quickly.
p.17
Energy Sources for Muscle Contraction
What happens during high intensity exercise regarding oxygen supply?
Oxygen supply is not sufficient for cellular requirements.
p.33
Muscle Fiber Types: Fast vs. Slow
What special feature is found in cardiac muscle?
Intercalated discs separating adjacent cells.
p.13
Oxygen Supply and Cellular Respiration
What type of respiration is aerobic respiration?
A complete breakdown of glucose that requires oxygen.
p.8
Muscle Relaxation Mechanisms
What is the significance of breaking the connection between myosin and actin?
It is necessary for muscle relaxation.
p.22
Role of Myosin and Actin in Muscle Contraction
What is the all-or-none response in muscle physiology?
When a muscle fiber contracts fully or not at all, depending on whether the stimulus reaches the threshold.
p.4
Sliding Filament Model of Muscle Contraction
What is the result of the repeated cycles of cross-bridge binding?
Filament sliding and muscle fiber shortening.
What happens when a muscle fiber cannot relax completely?
It reaches a point where the force of individual twitches combines through summation.
p.13
Oxygen Supply and Cellular Respiration
What role does hemoglobin play in the body?
Carries oxygen to muscle tissue.
p.15
Oxygen Supply and Cellular Respiration
What supports aerobic respiration during rest or moderate activity?
Sufficient oxygen availability.
p.32
Role of Myosin and Actin in Muscle Contraction
What are intercalated discs?
Complex membrane junctions that join cardiac muscle cells and transmit contraction force.
p.11
Energy Sources for Muscle Contraction
How is ATP regenerated for muscle contraction?
From creatine phosphate and cellular respiration.
p.1
Sliding Filament Model of Muscle Contraction
What happens to the actin filament as the myosin heads repeatedly attach and pull?
The filaments increase their overlap and the sarcomere shortens from both ends.
p.33
Types of Muscle Contractions
What is the major function of cardiac muscle?
Pumping action of the heart.
p.15
Oxygen Supply and Cellular Respiration
Where does lactate diffuse after being produced in muscle cells?
Into the bloodstream and then to the liver.
p.9
Role of Myosin and Actin in Muscle Contraction
What happens to tropomyosin when calcium binds to troponin?
Tropomyosin moves and exposes specific sites on actin.
p.9
Types of Muscle Contractions
What force does the muscle fiber exert during contraction?
A pulling force on its attachments.
p.29
Types of Muscle Contractions
Do muscles have to shorten to generate force?
No, muscles can generate force without shortening.
p.31
Types of Muscle Contractions
How does the speed of contraction compare between smooth and skeletal muscle?
Smooth muscle is slower to contract and relax.
p.31
Energy Sources for Muscle Contraction
How does smooth muscle maintain contraction compared to skeletal muscle?
Smooth muscle maintains a contraction longer with the same amount of ATP.
p.31
Types of Muscle Contractions
What unique ability does smooth muscle have regarding its length?
Smooth muscle can change length without a change in tautness.
p.19
Muscle Fiber Types: Fast vs. Slow
What are the characteristics of fast muscle fibers?
They have a large diameter, fatigue quickly, and are best for rapid, short-term activities.
p.12
Energy Sources for Muscle Contraction
How quickly can ATP be generated from creatine phosphate?
It provides a rapid but short-term energy supply.
p.13
Oxygen Supply and Cellular Respiration
What is the function of myoglobin in muscle tissue?
Stores oxygen for aerobic respiration, increasing oxygen availability.
p.24
Types of Muscle Contractions
What is complete tetanic contraction?
A sustained contraction that lacks any relaxation, achievable only in a lab.
p.7
Calcium Ion Release and Muscle Contraction
What interacts with troponin and tropomyosin to expose myosin binding sites?
High concentration of calcium in the sarcoplasm.
p.11
Energy Sources for Muscle Contraction
What must the cell rely on as the supply of creatine phosphate declines?
Cellular respiration to generate ATP.
p.9
Sliding Filament Model of Muscle Contraction
What is the result of the pulling of cross-bridges?
Thin filaments are pulled toward the center of the sarcomere.
p.34
Role of Myosin and Actin in Muscle Contraction
What are the two proteins associated with the surface of actin molecules?
Troponin and tropomyosin.
p.33
Types of Muscle Contractions
What is a key characteristic of cardiac muscle contraction?
Network of cells contracts as a unit; self-exciting; rhythmic.
